When you press the shutter release on a camera, there's usually a lag time
or delay before the shutter actually fires. This corresponds to the time required
for the autofocus and autoexposure mechanisms time to do their work, and can
amount to a fairly long delay in some situations. Since this number is rarely
reported on (and even more rarely reported accurately), and can significantly
affect the picture taking experience, I routinely measure both shutter delay
and shot to shot cycle times for all cameras I test, using a test system I designed
and built for the purpose. (Crystal-controlled, with a resolution of 0.001 second.)
Here are the numbers I collected for the Pentax Optio S5i:

Pentax Optio S5i Timings

Operation

Time
(secs)

Notes

Power On -> First shot

3.5

LCD turns on and lens extends forward. About average.

Shutdown

2.5 - 6.5

First time is time to retract lens, second time is worst-case time, with camera writing to the memory card. Fairly fast.

Play to Record, first shot

0.4

Time until first shot is captured. Very fast.

Record to play

4.5 / 0.4

First time is that required to display a large/fine file immediately after capture, second time is that needed to display a large/fine file that has already been processed and stored on the memory card. First time is rather slow, second is quite fast. (Note though, that the Instant Review feature does display the just-captured image almost immediately, within a half-second or less.)

Shutter lag, full autofocus

0.44 / 0.83

First time is at full wide-angle, second is full telephoto. First time is very fast, second is a little faster than average. (Both are very good for a subcompact digicam.)

Shutter lag, manual focus

0.14

Time to capture, manual focus. A good bit faster than average.

Shutter lag, prefocus

0.011

Time to capture, after half-pressing shutter button. Blazingly fast.

Cycle Time, max/min resolution

4.74 /
2.1

First number is for large/fine files, second number is time for "TV" mode (640x480) images. Times are averages. Buffer clears after each shot regardless of resolution. Both times are quite slow.

Cycle Time, continuous mode,
max/min resolution

3.46 / 0.99
(0.29 / 1.01fps)

First number is for large/fine files, second number is time for "TV" mode (640x480) images. Times are averages. Buffer clears after each shot regardless of resolution. Both times are rather slow.

Surprisingly fast shutter response, slow shot-to-shot cycle times.
With full-autofocus shutter lag ranging from 0.44 - 0.83 seconds, the Pentax
Optio S5i is surprisingly quick for a subcompact digital camera. (Although
0.83 seconds is still way too long to have to wait, if you care about fast-breaking
action.) At 0.14 seconds, its manual-focus shutter lag is better than most,
and its lag of only 0.011 second when "prefocused" by half-pressing
and holding down the shutter button prior to the shot itself is positively
blazing. Alas, like most subcompact digital cameras, its shot to shot cycle
times are downright lethargic, at an average of 4.7 seconds between shots
for large/fine images, and 2.1 seconds for small/basic quality ones. Continuous
mode is only slightly faster, at 3.5 seconds/frame for large/fine images,
or 0.99 seconds/frame for small/basic ones. Bottom line, not bad for fast
action, as long as you don't mind waiting a while between shots.

Power

The Pentax Optio S5i uses a custom rechargeable LiIon battery for power. Because
it uses a custom external power connector, I was unable to conduct my usual
direct power consumption measurements. I did time how long a fully-charged battery
pack took to run down in the worst-case power consumption mode (record mode,
with the rear-panel LCD illuminated), and found it to be a (very) respectable
111 minutes. While I always advise readers to purchase an extra battery right
along with their digicams, the S5i's battery life is quite good, especially
for a subcompact model.

Storage Capacity

The Pentax Optio S5i stores its photos on SD memory cards or approximately
10.2MB of internal memory. No memory card is included with the camera. (I strongly
recommend buying at least a 64 MB card, preferably a 128 MB one, to give yourself
enough space for extended outings.) The chart below shows how many images can
be stored in the internal memory at each size/quality setting, underscoring
the need for a separate memory card.

Image Capacity vs
Resolution/Quality
32 MB Memory Card

Fine

Normal

Basic

2560
x 1920

Images
(Avg size)

3
3.4 MB

5
1.7 MB

9
1.0 MB

Approx.
Compression

4:1

9:1

14:1

2048
x 1536

Images
(Avg size)

4
2.0 MB

9
1.1 MB

13
768 KB

Approx.
Compression

5:1

8:1

12:1

1600
x 1200

Images
(Avg size)

8
1.2 MB

14
716 KB

19
511 KB

Approx.
Compression

5:1

8:1

11:1

1024
x 768

Images
(Avg size)

18
563 KB

33
307 KB

43
235 KB

Approx.
Compression

4:1

8:1

10:1

640 x 480

Images
(Avg size)

39
256 KB

62
164 KB

83
123 KB

Approx.
Compression

4:1

6:1

8:1

Download Speed

The Pentax Optio S5i connects to a host computer via a USB interface. Downloading
files to my Sony desktop computer running Windows XP (Pentium IV, 2.4 GHz),
I clocked it at a relatively fast 763 KBytes/second. (Cameras with slow USB
interfaces run as low as 300 KB/s, cameras with fast v1.1 interfaces run as
high as 600 KB/s. Cameras with USB v2.0 interfaces run as fast as several
megabytes/second.)